The present application relates to a display device and an information processing apparatus using the same. More particularly, the application relates to a display device and an information processing apparatus with a light receiving function which is capable of maintaining a display quality even when a light receiving resolution is made lower in level than a display resolution.
A display device is proposed which has a display circuit and a light receiving circuit disposed on the same substrate, which displays thereon an image, and which can receive a light from the outside. This display device, for example, is described in Japanese Patent Laid-open Nos. 2000-19478 and 2006-127212. The light receiving circuit of the display device detects a light emitted from an object (such as a pen) having an external light source such as a light emitting diode (LED), a light in the form of which a light emitted from a back light is reflected by a finger or a pen touching a screen to return, or the like. The applicant of this application proposes a method of driving a light receiving circuit when detecting the light in the form of which a light emitted from a back light is reflected by a finger or a pen touching a screen to return in Japanese Patent Laid-open No. 2006-127212.
Each of Japanese Patent Laid-open Nos. 2000-19478 and 2006-127212 relates to a technique about a liquid crystal display device of a type in which the display circuit controls a liquid crystal. However, a display device which displays thereon an image and receives a light by using organic electro luminescence elements as self-light emitting elements is also known. This display device, for example, is described in Japanese Patent Laid-open Nos. 2004-127272 and 2005-293374.
In the liquid crystal display device having the display circuit and the light receiving circuits disposed on the same substrate, a light transmittance decreases because no light emitted from the back light penetrates through a region having the light receiving circuit disposed therein. Therefore, it is recommended that when a light receiving resolution at a high level is unnecessary for the display device, the number of light receiving circuits disposed on the substrate is reduced as much as possible, thereby making a light receiving resolution lower in level than a display resolution. With regard to the case where the light receiving resolution at the high level is unnecessary for the display device, for example, there is the case where an interface is specialized by using a touch sensor. In the interface using the touch sensor, it has to be determined whether or not a touch (depression) is made, or whether a movement is made in a touch state. Thus, the light receiving resolution at the high level is unnecessary for the display device. In addition, a size of the finger or pen touching the screen of a display panel is much larger than that of one pixel. Hence, it is also unnecessary to dispose light receiving sensors in all the pixels.
However, when the number of light receiving circuits is reduced, a user who sees an image displayed on the screen may feel a sense of incompatibility. For this reason, a problem may be caused in the display quality.